Melanoma or not? Cancer testis antigens may help

Cancer testis antigens (CTAs) are expressed in a variety of malignant tumours. No CTA expression is found in normal adult tissues, except in male germ cells and occasionally placenta. To date, more than 20 CTAs or antigen families have been identified.

Owing to their tumour-associated expression pattern, CTAs may be useful for making a distinction between benign and malignant neoplasms. The present study was done to analyse the value of CTAs for the discrimination of cutaneous melanoma and naevi.

Primary melanomas (38) and 19 naevi were analysed for their expression of CTAs by immunohistochemistry using the following monoclonal antibodies (mAb) to the following antigens (mAb/antigen): MA454/MAGE-A1, 57B/MAGE-A4, ES121/NY-ESO-1. In a subset of melanomas (n = 26), the CTA panel was extended to three additional CTAs (mAb/antigen): CT7-33/MAGE-C1, M3H67/MAGE-A3 and GAGE/GAGE.

All 19 naevi were negative for the mAbs MA454, M3H67, 57B, ES121, CT7-33 and GAGE. In melanoma, the immunoreactivity was as follows: MA454: 8/38 (21%), 57B 11/38 (29%), ES121 9/38 (24%). However, 19/38 (50%) were positive for at least one CTA. When 26 melanomas were tested for the expression of six different CTAs 20/26 (77%) were positive for at least one CTA.

CTAs may be useful in the determination of suspected malignancy in cutaneous melanomas. The low incidence of particular CTAs can be overcome by increasing the number of CTAs analysed.